Flexible joint means are used in many mechanical systems, both simple and complex. Flexible joints, especially flexible pipe joints, are one type of this family of joint means. An example of such a flexible joint is presented in FIG. 1. In operation, these flexible joint means are positioned in between other structures, such as pipes, and act, e.g., to “cushion” or to equilibrate pressure or other forces that are applied to the mechanical systems in which they are utilized. In essence, these joints serve to absorb stress and movement from the mechanical means of which they are a part. An example of a flexible joint, in operation, is shown in FIG. 2, where the flexible joint is positioned in between a part of pipe means, and is compressed. A depiction of such a joint under tension is shown in FIG. 3.
As may be gathered from, e.g., the figures, it is critical that flexible pipe joints, or any other joint, be installed properly and that their functioning be monitored carefully. If the joints are disposed improperly, an example of which is shown in FIG. 4, the results can include misalignment of the mechanical device in which the joints are deployed, excess or unequal pressure, and eventual malfunction of the devices and apparatus.
Various means are known for determining if a joint is deployed in such a way that excess pressure is measured. So-called “foil strain gages” represent an example of this. Such gages are attached to the joint, move up and down with the joint and measure strain applied thereto, providing an electronic signal which is read via an outside means, which in turn provides some sort of determinable signal. See, e.g., U.S. Pat. Nos. 7,111,688; 5,529,346; 6,631,928; 4,635,533; 4,099,746; and 3,845,657 all of which are incorporated by reference in their entirety as examples of various types and deployments of strain gages.
In considering the bases by which these devices function, it is important to keep the definitions of “strain” and ‘stress” that are used herein in mind. “Strain” is the amount of deformation of a body due to applied force, i.e., the amount of deformation, per unit length of an object, when a weight or pressure is applied. “Stress,” defined as the object's internal resisting force, is also called strain.
Measuring strain is certainly an important part of making sure an apparatus functions properly; however, the inventor has ascertained that the classical approach to measuring what is referred to as strain, can also be done so visually, and simply, by utilizing what will be referred to as a “level indicating means,” which is useful in determining whether or not strain has been placed on a joint means.